Field of the Invention
The present invention relates to an undercoat agent and a method of producing a structure containing a phase-separated structure.
Background Art
In recent years, the continued miniaturization of large scale integrated circuits (LSI) has led to demands for techniques capable of processing ever finer structures. In response to the demands, testing has commenced into the formation of finer patterns using phase-separated structures that are formed by the self-assembly of a block copolymer containing mutually incompatible blocks bonded together. (For an example, refer to JP-A-2008-36491).
To utilize the aforementioned type of phase-separated structure of a block copolymer, a self-assembled nanostructure formed by microphase separation must be formed only within a specific region, and must be oriented in the desired direction. To achieve this positional control and orientation control, processes such as graphoepitaxy, which controls the phase-separated pattern using a guide pattern, and chemical epitaxy, which controls the phase-separated pattern based on differences in the chemical state of the substrate, have been proposed (for an example, refer to Proceedings of SPIE, V. 7637, 76370G-1(2010)).
In the chemical epitaxy process, a neutralization film containing a surface treatment agent which has affinity with any of the blocks that constitute the block copolymer is disposed on the substrate surface in a predetermined pattern. By the pattern (guide pattern) of the neutralization film disposed on the substrate surface, orientation of each phase of the phase-separated structure is controlled. Therefore, to form a predetermined phase-separated structure, it is important to dispose the neutralization film in accordance with a period of the block copolymer.
For these block copolymers, block copolymers having a block formed from a repeating unit of a styrene and a block formed from a repeating unit of methyl methacrylate (PS-b-PMMA) are being widely investigated, and it is claimed that PS-b-PMMA is a material that can be used in the formation of very fine patterns down to approximately 13 nm.
Additionally, investigations are currently also being conducted into pattern formation methods using Si-containing block copolymers, which have been identified as materials potentially capable of realizing the formation of patterns of even finer dimensions. Block copolymer layers formed using these Si-containing block copolymers have low surface energy.